Don't confuse the INTERNET with its very limited predecesor, ARPANET.
Prior to the late 70's, early 80's access to the INTERNET was severly
restricted and even being at a location that was connected didn't
guarantee you would be allowed access. That is why many schools (and
other organizations, but mnostly schools) were on BITNET. General access
came much later. I was hired to make The University of Scranton the
first location in all of NE Pennsylvania to be "on the INTERNET". That
was in 1989. The first local ISP was several years later. Usenet
goes back to when connecting was done using UUCP, at night, over the
phone system. Access only required that you find someone willing ot
peer with you and you could afford the phone calls. :-)

I just looked it up. "The INTERNET" remained a DARPA project until
1975. At that point, access was still strictly limited. This is
was the same time that UUCP was developed. USENET islisted as being
"officially" started in 1979. "The INTERNET" is still considered
a DARPA Project. BITNET starts in 1981. CSNET is also formed at this
time. TCP/IP is published in 1982. In 1983 ARPANET adopts TCP/IP.
CSNET/ARPANET gateway is put in place. ARPANET splits off MILNET.
NSFNET starts in 1986. Access is still greatly restricted. Requests
to join NSFNET require justification. etc. etc.

Yeah, looks like Usenet was around long before what people think of
as the INTERNET. I have been doing Email and reading news since 1980.
I didn't have my first INTERNET connected account until 1988 and that
was through a government contrator I worked for.

The public INTERNET is much younger than most people realize. Computer
communications is at least twice as old.